JPH0989821A - Thermal analysis device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heating and cooling effect by optimizing the temperature control of a sample. SOLUTION: A sample container 2 is formed by a magnetic body and at the same time and is heated by electromagnetic induction 4. With this configuration, the sample container can be directly heated rather than the transfer of heat via a number of inclusions such as a reactor core tube and atmosphere from a heater as in a conventional device, thus reducing thermal loss on the way and minimizing power required for heating. Also, since thermal inertial is small, the fidelity of temperature control (following property to an expected temperature program) can be improved. Even in the case of cooling after measurement is completed, only the sample container and the sample may be cooled, thus drastically reducing time required for cooling as compared with a case for cooling a conventional reactor core tube and atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample heating means and method in various thermal analysis devices and methods.

[0002]

2. Description of the Related Art A test method for examining the thermal characteristics of various materials and the stability of various inorganic and organic compounds.
One is thermal analysis. Thermogravimetry (T) is used to determine the thermal stability from the change in weight of a sample while heating it at a constant rate or maintaining it at a constant temperature.
G) or the differential thermal analysis (differential t analysis) to examine the change in the state of the sample by measuring the temperature difference between them while heating or cooling the sample with a thermally inactive reference substance at a constant rate.
hermal analysis (DTA), and thermomechanical analysis (TMA) that measures the dimensional change of a sample while it is heated and subjected to a load such as compression and tension.

The analysis temperature range is usually from room temperature to about 1500 ° C. and may be maintained at a predetermined temperature. However, when a temperature change is required, scanning is performed at a constant temperature change rate, for example, 10 ° C./min. . The sample is solid or liquid, and the test piece is held in a heating furnace, or the diameter of a few mg to several tens of mg is measured.
Store in a container with a depth of 6 mm and a depth of 2 mm for measurement. As a heating furnace, generally, a cylindrical ceramic enclosure for maintaining an atmosphere of a sample is provided, and a heating wire such as a nichrome wire is wound around the enclosure is generally used. The sample is placed in this heating furnace, and the temperature of the sample or the inside of the heating furnace is monitored by a temperature measuring means such as a thermocouple, and the sample is maintained at a predetermined temperature or the temperature of the sample is separately detected while the temperature of the sample is separately detected. The thermal characteristics and physical properties are investigated by the measuring means.

[0004]

In any of the thermal analysis methods, it is necessary to control the temperature of the sample with high accuracy in order to perform highly accurate and stable measurement, and the temperature gradient in the sample is small. Since it is more desirable, the heating furnace is made larger so that the distance from the sample to the heater is secured, unevenness of heat transfer to the sample is reduced, and the propagation of temperature fluctuation due to control is prevented. Therefore, at present, it is impossible to realize the downsizing and space saving of the entire apparatus due to the increase in the size of the heating furnace. In addition, since the entire atmosphere such as air and nitrogen filled in the heating furnace must be heated, even though the sample to be heated is only a few tens of milligrams, it takes a few times for heating. A large power of 100 W to 1 KW or more is required. Furthermore, the large heat capacity of the heating furnace itself and the large thermal resistance of the atmosphere cause thermal inertia, which deteriorates the responsiveness of the temperature control of the sample. Also,
As another adverse effect, since it takes a long time to cool the furnace after the measurement, the work efficiency is deteriorated such that the measurement cannot be immediately performed.

[0005]

In order to solve the above-mentioned problems, in the thermal analysis apparatus according to the present invention, sample holding means at least a part of which is made of a magnetic material, and the sample holding means are subjected to electromagnetic induction heating. The electromagnetic induction heating means, the temperature measuring means for monitoring the sample temperature, and the measuring means for detecting the state change of the sample. Further, the thermal analysis method according to the present invention is characterized in that the sample or sample holding means at least a part of which is made of a magnetic material is heated by electromagnetic induction.

As the sample holding means, the sample container itself may be made of a magnetic material such as nickel, or the magnetic material may be mixed in glass, heat resistant plastic or ceramic. Further, the sample container itself may be made of a non-magnetic material and a magnetic adapter for accommodating the sample container may be separately provided. Alternatively, when the sample itself is a magnetic substance, the sample itself may be directly heated by electromagnetic induction.

The electromagnetic induction heating (IH) means is realized by a publicly known and used high frequency power source, an inverter control circuit, an IH coil and the like.

As a measuring means for detecting a change in the state of the sample, it is adopted according to various thermal analysis methods. For example, in the case of TG, it is a balance, and in the case of DTA, it is a means such as a thermocouple that detects the temperature difference between the reference substance and the sample.

As the temperature measuring means of the sample, there are known ones such as a thermocouple which is generally used in a thermal analyzer for directly contacting the sample for measurement, and other non-contact measurement such as radiation type. The temperature measuring means of is applied.

Further, it is usually preferable to provide a temperature adjusting means for feeding back to the heating means so that the measured value from the temperature measuring means follows the desired temperature program.

Further, by providing an enclosure (partition) which can shield the atmosphere of the sample or the sample container from the outside, the desired sample atmosphere (in addition to air, an inert gas, a reducing gas, etc.)
Can be adjusted to.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a thermogravimetric measuring device. The thermogravimetric measuring device 1 includes a sample container 2 made of a magnetic material such as nickel or magnetic stainless steel.
A solid or liquid sample S is put in and is connected by a suspension wire 7 to a mass measuring mechanism (not shown) such as a balance. The sample container 2 is placed in a partition 3 made of quartz glass, for example, and the sample atmosphere is shielded from the outside. A high-frequency current coil 4 is arranged outside the partition 3 and around the sample container 2, and is connected to equipment such as a high-frequency power supply and an inverter control circuit (not shown) required for electromagnetic induction heating.

In the high frequency current coil 4, for example, several W to several tens W
When a high frequency current of about 22 to 40 KHz is applied, the sample container 2 made of a magnetic material is placed inside the coil 4.
Eddy current is generated in the sample, and the sample S in the sample container 2 is heated by the self-heating caused by the Joule heat. For the temperature of the sample S, a temperature measuring means such as a thermocouple is installed near the sample in the sample S, or a sample such as a radiation thermometer for measuring the surface temperature (color temperature) of the bottom surface of the sample container 2 as shown in FIG. The heating power is adjusted by controlling the frequency of the inverter circuit so that the temperature measured by the temperature detector 5 coincides with the desired temperature. In this way, the sample S is accurately controlled to the desired temperature, the change in weight when the temperature changes is measured by a mass measuring means such as a balance connected to the end of the suspension wire 7, and TG is performed.

[0015]

Example Instead of the sample container 2 made of a magnetic material as described above, a sample container 2 made of a non-magnetic material and an adapter 6 made of a magnetic material for accommodating the sample container 2 may be used (FIG. 2). The sample container 2 needs to be made of a material that does not react with the sample itself even when it is heated at a high temperature. By using such an adapter, the selection range of the material of the sample container is expanded, and the sample to be measured is Depending on the analysis, the sample container 2, which may be contaminated during the analysis, can be replaced for each analysis, while the suspension wire 7 can be fixed to the adapter 6 that accommodates it and used repeatedly.

When the present invention is applied to a differential scanning calorimeter equipped with a conventional soaking block, such a soaking block is completely abolished, and a self-heating system of only the sample container is used as in the above embodiment. can do. Alternatively, it is also possible to provide a magnetic cover that covers the entire surface of the soaking block, including the top and bottom surfaces, and generate an eddy current in this cover to form a thermally uniform furnace body.

[0017]

According to the structure of the present invention, heat is transferred from a heating element such as a heater through a furnace core tube, an atmosphere, a sample container, a sample and many inclusions like a heating furnace of a conventional thermal analyzer. Since the sample (container) can be heated directly, the effective heat capacity of the heated part and the heat loss in the middle are also small, and the power required for heating is the minimum (number of W to several tens of W) is sufficient. Moreover, since the thermal inertia is small, the fidelity of temperature control (following the desired temperature program) is improved. During heating, an eddy current is generated two-dimensionally over the entire surface of the sample container, so that the temperature distribution in the sample becomes more uniform and good analysis results can be obtained. Even when cooling after measurement (forced air cooling with a blower, etc.), it is sufficient to cool only the sample container and sample, and the time required for cooling is dramatically reduced compared to the conventional cooling of the core tube and atmosphere. can do.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of a thermal analysis device according to the present invention.

FIG. 2 is a schematic diagram showing a configuration example of a sample container of the thermal analysis device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Thermogravimetric measuring device 2 ... Sample container 3 ... Partition wall 4 ... High frequency current coil 5 ... Sample temperature detector 6 ... Adapter S ... Sample

Claims (2)

[Claims] 1. A sample holding means at least a part of which is made of a magnetic material, an electromagnetic induction heating means for heating the sample holding means by electromagnetic induction, a temperature measuring means for monitoring the sample temperature, and a change in the state of the sample is detected. A thermal analysis device comprising: 2. A thermal analysis method comprising heating a sample holding means or a sample, at least a part of which is made of a magnetic material, by electromagnetic induction.